Ferrous alloy



April 18, 1933. R Q DEAN 1,904,859

FERR'oUs ALLOY Filed March 24, 1930 3 Sheets-Sheet l /aaaa :be 4.00 an am /aa /zaa Ma /m /u @WM #y April 18, 1933. R, s. DEAN 1,904,859

FERROUS ALLOY zada R. S. DEAN FERROUS ALLOY lApril 18, 1933.

Filed March 24, 1930 3 Sheets-Sheet 3 Patented Apr. 18, 1933 UNITED STATES PATENT OFFICE mienunn s. DEAN, or WASHINGTON, :DISTRICT oF comnuau, AssIGNon To WESTERN ELECTRIC COMPANY, INCORPORATED, 0F NEW YORK, N.

NEW YORK I'Emous ALLOY Application led Iarch 24, 1930. Serial No. 488m. v

This invention relates to `ferrous alloys and methodsof producing the same, and more particularly to alloys of iron with tungsten, molybdenum, beryllium, and tantalum, and to methods of treating such alloys so as to produce certain desirable mechanlcal and magnetic characteristics. l

An object of the invention 1s to provlde an alloy in which certain desirable physical and magnetic properties are produced by special treatment.

In accordance with the generalfeatures. of the invention as embodied in one specific form thereof, a quantity of iron, preferably substantially free of carbon, 1s alloyed with one or more of the above named alloy 1ngredients, and the mass is then cast 1n the form of ingots, which are then formed by forging or other means into any desired shape, or such shapes may 1f des1red be formed directly from the molten metal. The forgings are then heated to a temperature just below the eutectic point of the alloy, and this temperature is maintained for a sufficiently long period of time to cause substantially all of the resulting solute constituent to enter solution in the iron, and the alloy 1s then quenched at a suiiiciently rapid rate to cause the solute constituent to remain in the iron in the form of a supersaturated solid solution, after which the alloy is caused to assume a more stable state by aging. The hardness of the alloy as quenched may be increased considerably by such aging, and the secondary hardness is retained even at elevated temperatures. In the manufacture of articles such as dies or permanent magnets from alloys of the type just described, an article may be forged or otherwise formed from the alloy and the formed article then subjected to the above outlined heating, cooling. and aging operations.

The above described and otherobjects and features of the invention will be apparent from the following detailed description, taken in connection with the accompanying drawings, in which Fig. l is a graphic representation of certain phenomena encountered in the aging of an Y., A. CORPORATION OI' iron-tungsten alloy containing 21.1% of tungsten;

Fig. 2 is a similar representation `of the properties of an iron-molybdenum alloy containing 23.4% of molybdenum;

Fig. 3 is a similar representation of the properties of an iron-beryllium alloy containing 2.8% of beryllium;

Fig. 4 is a similarlrepresentation of the properties of an iron-tantalum alloy containing?24% of tantalum.; and 1 ig. 5 i's a similarrepresentation of the properties of a quaternary alloy containing approximately 25.7% cobalt, 20.1% tungsten, 6.4% manganese, and the remainder iron.

This invention is based on the discovery that the mechanical properties of the above named alloys, as well as the magnetic remanence and coercive force, may be greatly in creased by a proper heat treatin process, and the magnetic characteristics o the alloy will not necessarilyl vary with its physical hardness.

Although it is not known with certainty what the solute constituents of these alloys are, it is believed that the alloy ingredient combines chemically with a part of the iron to form a compound which remains in a dispersed phase throughout the iron and may under certain conditions be' precipitated in the form of microscopic or submicroscopic particles dispersed throughout the alloy. The various steps constituting the processes describedv below are the same regardless of Whether the alloy ingredient is dissolved the iron as an element or as a compound, and it is to be understood, therefore, that in the following description and appended claims the term solute constituent may include the alloy ingredient either combined or uncombined as the case may actually be. y

In practicing-"one method of producing alloys inaccordance with quantity of tungsten, molybdenum, beryllium or tantalum .greater than that which will enter'solution -iniron at room temperature, but not substantially more than is soluble at the eutectic` temperature, is alloyed with ironland the resultin alloy is caused to solidify. The alloy is t en heated at a the invention, a

temperature dependent upon which alloy ingredient is used until a substantially homogeneous solid solution is formed, and is then quenched at a rate sufficiently rapid to cause most or all of the alloyv ingredient to be ret-aiued in the iron in the form of a supersaturated solid solution, and the alloy is subsequently aged at a temperature considerably below the eutectic temperature. The proper length of time and temperature of the solution forming step, quenching or supersaturating step, and the aging step, wherein the alloy is allowed to assume a more stable state, together with the proper proportions of iron and alloy ingredient, will vary with tlze properties desired in the alloy and the uses to which the alloy is to be put as well as with the particular alloy ingredient employed. However, the following example has been found to produce a satisfactory alloy for permanent magnets. To a substantially carbon-free iron is added 21.1 parts of tungsten, and the two ingredients are agitated in any known manner while in the molten state to produce a homogeneous alloy. The alloy is then cast into ingots and fabricated into desired shapes, which are then brought to a temperature (about 2600o F. in the case of tungsten) slightly below the eutectic temperature, and maintained at such temperature for a sufficient time to produce a solid solution of the tungsten in the iron. The parts are then quickly cooled by quenching, thus producing a solid solution of the solute constituent in the iron. The parts are then heated to about 1400o F., and maintained at such temperature for a time varying from fifteen minutes to an hour, after which they are quenched either rapidly or slowly, the rate of coolingebeing immaterial. The alloy, after this treatment, will be found to have a magnetic remanence or coercive force higher than that of iron-tungsten alloys heretofore produced, and is suitable for use in permanent magnets. Referring to the drawings, curve B of Fig. 1 indicates the magnetic remanence obtained by treating the alloy at various temperatures for one hour, cooling, and then subjecting the parts to a magnetizing force of 1000 gilberts per centimeter. The coercive force is indicated in curve C, and mechanicalo hardness in curve A. All these characteristics are at or near a maximum when the alloy is aged at about 1400 F. An alloy aged at that temperature, in addition to having desirable magnetic characteristics, is suitable for use in dies for die casting lmachines and for analogous uses since it is capable of withstanding-high temperatures without losing its hardness.

Fig. 2 illustrates the behavior of an ironmolybdenum alloy containing 23.4% of molybdenum, curve D representing the variation in hardness while curves E and F repre-y `hardness while\eurves H and I represent remanence and coercive force respectively. It will be noted that in the case of this alloy the remanence reaches its maximum value at a. considerably higher aging temperature than the coercive force and hardness.

Fig. 4 illustrates the behavior of an irontantalum alloy containing 21.9% of tantalum,

curve J representing the variation in hardness while curves K and L represent remanence and/ coercive force respectively, all of which characteristics reach their maxima at or near 13009 F.

Fig. 5 illustrates the behavior of a quaternary alloy containing approximately 25.7% cobalt, 20.1% tungsten, 6.4% manganese, and the remainder substantially carbon-free iron. The figure shows that the mechanical hardness, represented by curve M, reaches a maX- imum when the alloy is aged at a temperature of about 1100o F., whereas the remanence, represented by curve N, and the coercive force, represented by curve O, reach their maximum values at considerably higher aging temperatures. The figure also illustrates the possibility of adding alloy ingredients in addition to tungsten, molybdenum, beryllium, and/or tantalum to 1mprove the mechanical characteristics of the alloy, even though the additional alloy ingredients do not themselves form age-hardenable alloys with iron.

Alloys produced in accordance with the process herein disclosed may be used for a variety of other purposes, and it is within the scope of this invention to add to the 'alloy more than one of the above named metals, as well as such other ingredients as may be found desirable to adapt the alloy to the special purposes to whichl it is to be put, thus producing ternary and quaternary alloys having such special properties as are necessar to meet special requirements.

t is to be understood that the invention is not limited to the precise temperatures and proportions mentioned herein, which may be varied considerably without departing from the spirit of the invention as defined in the appended claims.

What is claimed is: 1. The method of producing a permanent magnet which comprises alloying a metal of the group including tungsten, molybdenum,

beryllium, and tantalum with substantially carbon-free iron, forming a magnet of the alloy, heating the alloy to forma substantially homogeneous solid solution, cooling the solution at a rate to form a supersaturated solution, heat treating the magnet to develop its magnetic properties, and subjecting the magnet to a magnetizing force to magnetlze the magnet.

2. A magnetic alloy of a substantially carbon-free iron with substantially 21.1% tungsten in which the tungsten is present in supersaturated solution and heat treated at a temperature of substantially 1400 F. to develop its optimum magnetic properties.

3. VA magnetic alloy of a substantially car, bon-free iron with substantially 23.4% molybdenum in which the molybdenum is present in supersaturated solution and heat l5 treated at a temperature of substantiall 1200 F. to develop its optimum magnetlc A properties.

4. A magnetic alloy of substantiall carbon-free iron with substantially 2.8% beryl lium, in which the beryllium is present in supersaturated solution and heat treated at a temperature between 1000 and 1200 F. to develop its optimum magnetic properties.

5. A magnetic alloy of substantially car-V` bon-free iron with substantially 21.9% of tantalum in which the tantalum is present in supersaturated solution and heat treated at a temperature between 1200 yand 1400 F. to develop its optimum ma etic properties.

6. An alloy of substantially carbon-free iron with approximately 25% cobalt, 20% tungsten, in which the tungsten is present in supersaturated solution, heat-treated at a temperature of substantially 1400 F. to ageharden the alloy.

7 An alloy of substantially carbon-free iron with approximately 25% cobalt, 23% molybdenum, present in supersaturated solution, heattreated at a temperature of substantially 1300 F. to age-harden the alloy.

8. An alloy of substantially carbon-free iron with approximately 25% cobalt, and a metal of the group of tungsten, molybdenum, beryllium and tantalum, having the metal of the group present in supersaturated solution and heat-treated to age-harden the alloy.

9. A method of making an alloy which comprises alloying iron with cobalt and a metal of the group of tungsten, molybdenum, beryllium, and tantalum, heating the alloy to substantially the eutectic temperature of the metal of the group, quenching the alloy to produce a supersaturated solution of the metal of the group in the alloy, and a ehardening the alloy at a temperature to isperse the metal of the group in the alloy.

10. A method of making an alloy which comprises alloying iron with cobalt and tungsten in which the cobalt is present in the order of 25% and tungsten in the order of 20%, heating the alloy tol a temperature of approximate y 2600 F. to form a solid solution of the tungsten in the alloy, quenching the alloy to form a supersaturatedsoin which the molybdenum is the order of 25% and molybdenum inthe order of 23%, heating the alloy to a temperature of approximately the eutectic temperature of molybdenum te form a solid soi lution of the molybdenum in the alloy, quenching the alloy to form a supersaturated solution of the molybdenum in the alloy, and age-hardening the alloy at a temperature of approximately 1300 F.

12. A method of making an alloy which comprises alloying iron with cobalt, magnesium, and a metal of the group of tungsten, molybdenum, beryllium, and tantalum, heating the alloy to substantially the eutectic temperature of the metal vof the group to form a solid solution of the metal of the roup in the alloy, quenching the alloy to germ a supersaturated solution, and age-v hardening the alloy to disperse the metal of the group in the alloy.

In witness whereof, I hereunto subscribe my name this 3rd day of March A. D., 1930.

REGINALD S. DEAN. 

